The contrasting reactivity of trans- vs. cis-azobenzenes (ArN[double bond, length as m-dash]NAr) with benzynes.

Abstract

We report here a study that has revealed two distinct modes of reactivity of azobenzene derivatives (ArN[double bond, length as m-dash]NAr) with benzynes, depending on whether the aryne reacts with a trans- or a cis-azobenzene geometric isomer. Under thermal conditions, trans-azobenzenes engage benzyne via an initial [2 + 2] trapping event, a process analogous to known reactions of benzynes with diarylimines (ArC[double bond, length as m-dash]NAr). This is followed by an electrocyclic ring opening/closing sequence to furnish dihydrophenazine derivatives, subjects of contemporary interest in other fields (e.g., electronic and photonic materials). In contrast, when the benzyne is attacked by a cis-azobenzene, formation of aminocarbazole derivatives occurs via an alternative, net (3 + 2) pathway. We have explored these complementary orthogonal processes both experimentally and computationally.

• Authors: Dorian S Sneddon, Thomas R Hoye
• Journal: Chemical science (Chem Sci) Vol. 14 Issue 24 Pg. 6730-6737 (Jun 21 2023) ISSN: 2041-6520 [Print] England
• PMID: 37350825 (Publication Type: Journal Article)
• Copyright: This journal is © The Royal Society of Chemistry.